The present disclosure herein relates to a process and apparatus for forming steel workpieces, especially high strength steel workpieces, using an electrical current passing therethrough.
There are high requirements in terms of vehicle components with lightweight properties and high strength due to fuel efficiency regulations and strengthening of safety laws. Ultra high strength steel workpieces having strength over 1 GPa have been commercialized, and recently, development of steel having strength over 2 GPa is proceeding.
In general, if a steel plate increases in strength, then the steel plate decreases in elongation and is deteriorated in machinability or formability. To solve this limitation, a new technology that is so-called hot stamping process was suggested. In the hot stamping process, a steel plate is heated at a temperature of about 900° C. and press-formed, and thus formability is very excellent.
However, the workpieces strengthened by the hot stamping causes another problem, trimming. To trim high strength steel using a press, the trimming tool may be frequently broken, and thus trimming using the press cannot be applied to mass production of the high strength steel components. At present, a laser is used to trim the hot-stamped high strength steel workpiece.